The present invention relates to perpendicular magnetic recording systems. Conventional perpendicular magnetic recording systems use Giant Magneto-Resistive (GMR) sensors to achieve high readback performance. One type of perpendicular recording system uses a Current Perpendicular to the Plane GMR (CPPGMR) sensor. In a read head that employs a CPPGMR sensor, a permanent magnet (PM) abutted to a CPPGMR sense element is used to provide a 90 degree bias angle between magnetizations in adjacent anti-ferromagnetic free layers of the GMR stack. With the PM biasing scheme, however, the 90 degree bias angle is achieved only in the center of the GMR stack where the signal flux is decayed by 50%. At the air bearing surface (ABS) where the signal flux is maximal, there is almost no bias. This results in gross asymmetry in the readback signal and loss of readback signal strength. While it is expected that the geometry and high AR/R of the CPPGMR sensor will become increasingly important at very high density, the asymmetry problem will limit the performance of the CPPGMR sensor.
In addition, the abutted PM junction is difficult to fabricate at extremely small dimensions that typically characterize applications of CPPGMR sensors. This fabrication problem is aggravated by the need to have the PM be electrically insulated from, yet magnetically coupled to, the CPPGMR sensor.